Acta Anthropologica Sinica ›› 2024, Vol. 43 ›› Issue (06): 1027-1037.doi: 10.16359/j.1000-3193/AAS.2024.0012

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A supernumerary tooth of the Liujiang Man from the Tongtianyan cave site in Guangxi

SUN Qiyahui1,2(), XING Song1()   

  1. 1. Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044
    2. College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049
  • Received:2023-05-22 Revised:2023-07-20 Online:2024-12-15 Published:2024-11-28

Abstract:

Hyperdontia or supernumerary (or extra) teeth is one of the most common developmental anomalies in modern humans. Most supernumerary teeth are typically found in the maxillary anterior region, with about half occurring along the midline of the maxilla between the two central incisors, known as mesiodens. While supernumerary teeth have been extensively documented clinically, reports of such cases in human fossils are rare. This study describes a mesiodens embedded in the mid-palatal region of the Liujiang cranium, which is an early modern human from the Late Pleistocene in southern China discovered in the 1950s. The Liujiang mesiodens is partially exposed near the intermaxillary suture on the right side of the hard palate. High-resolution microcomputed tomography and three-dimensional virtual reconstruction further revealed that the mesiodens is conical in shape and horizontally positioned in the hard palate, with its long axis parallel to the intermaxillary suture. This mesiodens is situated distally to the long axis of the right central incisors with its cuspal apex facing the back of the palate, thus it is classified as a labiopalatinal type. Its crown corresponds to the position of the second premolar, away from the alveolar bone. Despite some distinctive features the location, shape, and direction of the Liujiang mesiodens overlapped with certain cases found in modern humans including that those from the Early Holocene. Based on clinical observations of pathological cases in modern humans, it is proposed that the Liujiang mesiodens may have migrated from the anterior region of the maxilla to the mid-palatal area. During this migration process, this supernumerary tooth adjusted its long axis from its original inverted form to its current horizontal position. This study provides evidence, dating back to the Late Pleistocene early modern humans for the occurrence of a horizontally positioned mesiodens in the mid-palatal region. Additionally, the Liujiang mesiodens presents early fossil evidence of supernumerary teeth in this special position and form than previously reported, as well as offers a case for the paleopathological study of abnormal number and position of teeth.

Key words: Early modern human, Supernumerary tooth, Paleopathology, Dental anomaly

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